Fields company purchased equipment on january 1 for $180,000. this system has a useful life of 8 years and a salvage value of $20,000. the company estimates that the equipment will produce 40,000 units over its 8-year useful life. actual units produced are: year 1 – 4,000 units; year 2 – 6,000 units; year 3 – 8,000 units; year 4 – 5,000 units; year 5 – 4,000 units; year 6 – 5,000 units; year 7 – 7,000 units; year 8 – 3,000 units. what would be the depreciation expense for the second year of its useful life using the units-of-production method? a) 20,000 b) 16,000 c) 24,000 d) 45,000 d) 33,750